Final Shuttle Flight Delayed Until November

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CAPE CANAVERAL, FL - JULY 31: Space Shuttle Endeavour touches down at the shuttle landing facility at Kennedy Space Center in Cape Canaveral, Florida, July 31, 2009. Endeavour was returning from a successful construction mission to the International Space Station. (Photo by Matt Stroshane/Getty Images)

Updated at 10:30 AM PDT on Monday, Apr 26, 2010

CAPE CANAVERAL, Fla. - The space shuttle's last big-time science experiment, the Alpha Magnetic Spectrometer, has delayed the end of the shuttle era from mid-September to at least mid-November.

The $1.5 billion particle detector is to be mounted on the station for an extended series of physics experiments, including a search for the universe's mysterious dark matter. The spectrometer may also help scientists gain new insights into the nature of antimatter and the origins of cosmic rays.

The spectrometer had been scheduled to fly aboard the shuttle Endeavour to the International Space Station in July. But NASA says the 7-ton instrument's supercooled, superconducting magnet must be replaced with a different type of magnet to extend its lifetime from a few years to a decade. To do this, scientists need more time, and NASA has decided to rearrange the launch dates of its final three space shuttles.

The upcoming flight of the shuttle Atlantis remains on schedule for launch no earlier than May 14. But the July flight of the shuttle Endeavour carrying the spectrometer will now leapfrog the shuttle Discovery's launch, currently set for Sept. 16.

Endeavour's mission will now be launched no earlier than mid-November, NASA says.

NASA has the funds and the spending authority to fly the space shuttle until year's end if needed.

Scientists decided to replace the magnet in part because the Obama administration called for the extension of space station operations from 2015 to 2020. Without the switchover, the spectrometer would essentially have been a useless appendage on the station for more than five years.